As is well known in the art, central inverter based energy conversion installations use groups of DC power sources connected in series, sometimes called strings. Examples include biomass, chemical, fuel cells and energy storage batteries. However, long strings of such sources have inherent deficiencies. For example, in the case of solar panels, if panels are shaded or obscured, they generate less photocurrent. Panel currents also may be unbalanced for other reasons. Because solar panels in a series string are constrained to all conduct the same current, the weakest one will limit the power harvest from the remaining solar panels, thereby reducing the overall efficiency of the array. For similar reasons, solar panels in a string should be given the same orientation and be of identical type and size. This is not always possible or desirable for aesthetic or other architectural reasons.
Another well-known approach is the microinverter. Microinverters convert solar energy from a single solar panel for feeding to the commercial AC power grid. Although MPPT is done on a per panel basis, thereby maximizing energy harvesting, cost effectiveness of microinverter installations are low due to higher cost per watt and lower efficiency of the electrical conversion.